Preliminary Incidence and Trends of Infections With Pathogens Transmitted Commonly Through Food

Foodborne Diseases Active Surveillance Network, 10 U.S. Sites, 2016-2019

Danielle M. Tack, DVM; Logan Ray, MPH; Patricia M. Griffin, MD; Paul R. Cieslak, MD; John Dunn, DVM; Tamara Rissman, MPH; Rachel Jervis, MPH; Sarah Lathrop, PhD; Alison Muse, MPH; Monique Duwell, MD; Kirk Smith, DVM; Melissa Tobin-D'Angelo, MD; Duc J. Vugia, MD; Joanna Zablotsky Kufel, PhD; Beverly J. Wolpert, PhD; Robert Tauxe, MD; Daniel C. Payne, PhD


Morbidity and Mortality Weekly Report. 2020;69(17):509-514. 

In This Article

Abstract and Introduction


To evaluate progress toward prevention of enteric illnesses, the Foodborne Diseases Active Surveillance Network (FoodNet) of CDC's Emerging Infections Program monitors the incidence of laboratory-diagnosed infections caused by eight pathogens transmitted commonly through food at 10 U.S. sites.* This report summarizes preliminary 2019 data and describes changes in incidence compared with that during 2016–2018. The incidence of enteric infections caused by these eight pathogens reported by FoodNet sites in 2019 continued to increase or remained unchanged, indicating progress in controlling major foodborne pathogens in the United States has stalled. Campylobacter and Salmonella caused the largest proportion of illnesses; trends in incidence varied by Salmonella serotype. Widespread adoption of whole genome sequencing (WGS) of bacteria has improved the ability to identify outbreaks, emerging strains, and sources of pathogens. To maximize the potential of WGS to link illnesses to particular sources, testing of isolates by clinical and public health laboratories is needed. Reductions in Salmonella serotype Typhimurium suggest that targeted interventions (e.g., vaccinating chickens and other food animals) might decrease human infections. Reducing contamination during food production, processing, and preparation will require more widespread implementation of known prevention measures and of new strategies that target particular pathogens and serotypes.

Members of FoodNet conduct active, population-based surveillance for laboratory-diagnosed infections caused by Campylobacter, Cyclospora, Listeria, Salmonella, Shiga toxin-producing Escherichia coli (STEC), Shigella, Vibrio, and Yersinia at 10 sites covering approximately 15% of the U.S. population (an estimated 49 million persons in 2018). FoodNet is a collaboration of CDC, 10 state health departments, the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS), and the Food and Drug Administration (FDA). Bacterial infections are defined as isolation of the bacteria from a clinical specimen by culture or detection of pathogen antigen, nucleic acid sequences, or, for STEC, Shiga toxin or Shiga toxin genes, by a culture-independent diagnostic test (CIDT).§ A CIDT-positive–only bacterial infection is a positive CIDT result not confirmed by culture. Listeria infections are defined as isolation of L. monocytogenes or detection of its nucleic acid sequences from a normally sterile site, or from placental or fetal tissue in the instance of miscarriage or stillbirth. Cyclospora infections are defined as detection of the parasite by microscopy using ultraviolet fluorescence or specific stains or by polymerase chain reaction. Cases with no documentation of international travel or unknown travel are considered domestically acquired infections.** The patient's disposition at hospital discharge, or 7 days after specimen collection if not hospitalized, is attributed to the infection.

Incidence per 100,000 population was calculated by dividing the number of infections in 2019 by the U.S. Census estimates of the surveillance area population for 2018. Incidence measures include all laboratory-diagnosed infections. A negative binomial model with 95% confidence intervals (CIs) was used to estimate change in incidence during 2019 compared with that during 2016–2018, adjusting for changes in the population over time; CIs not including zero were considered statistically significant. Analyses were performed using SAS statistical software (version 9.4; SAS Institute).

Surveillance for physician-diagnosed post-diarrheal hemolytic uremic syndrome (HUS), a complication of STEC infection characterized by renal failure, thrombocytopenia, and microangiopathic anemia, is conducted by reviewing hospital discharge data and by working with a network of nephrologists and infection preventionists. This report includes HUS data for children for 2018, the most recent year for which data are available.

*Connecticut, Georgia, Maryland, Minnesota, New Mexico, Oregon, Tennessee, and selected counties in California, Colorado, and New York (
STEC infections are defined as identification of Shiga toxin or its genes by any laboratory.
§A CIDT detects the presence of a specific antibody or antigen or the DNA of an organism.
Serogroup or serotype is only available for infections confirmed by culture.
**No international travel or not known if international travel occurred within 30 days before illness onset for Listeria, Salmonella serotypes Typhi and Paratyphi, 15 days for Cyclospora, and 7 days for all other pathogens.